This invention pertains to electrochemical cells and in particular to lithium cells comprised of a lithium metal anode(s) coated with Li ion conductive solid polymer electrolyte, a porous carbon cathode current collector, and a liquid electrolyte solution of lithium tetrachloroaluminate dissolved in an oxyhalide solvent. An example of this type of electrochemical cell is the Lithium/Thionyl Chloride (Li/SOCl.sub.2) or the Lithium/Sulfuryl Chloride (Li/SO.sub.2 Cl.sub.2) cell. The Li/SOCl.sub.2 cell has been known as a power source for consumer applications such as pacemakers, electronic devices, and watches, and for many military applications such as missiles and torpedoes. The attractiveness of this electrochemical cell results from its high cell voltage, usually between 3 V and 3.6 V depending upon the power drain rate, and its high energy density.
In Li/SOCl.sub.2 and Li/SO.sub.2 Cl.sub.2 cells the highly oxidizing sulfur oxychloride liquid electrolyte is in direct contact with the Li anode. Despite this, the cells are stable because when Li comes in contact with SOCl.sub.2 or SO.sub.2 Cl.sub.2 it reacts and forms a compact, protective film of LiCl on its surface. This LiCl protective film functions as a solid electrolyte interphase allowing the transport of Li ions across it while preventing the direct transfer of electrons from Li to SOCl.sub.2. This special feature of the lithium-sulfur oxychloride cells allows the fabrication of stable electrochemical cells. An undesirable feature of these cells, however, is that, when they are stored, the LiCl film increases in thickness. The film growth rate is a function of the storage temperature, with the rate increasing at higher temperatures. For example, the LiCl film attains a thickness of 2,000-10,000 .ANG. when a Li/SOCl.sub.2 cell is stored at 70.degree. C. for two weeks. The LiCl film is a poor Li ion conductor with a conductivity of less than 10.sup.-9 (ohm-cm).sup.- 1. In a freshly prepared cell in which the anode film is thin, the voltage loss due to the resistivity of the film when the cell is placed under load (i.e., discharged) is small. On the other hand, when an identical cell is discharged after a certain period of storage, there is a significant delay in its voltage before it rises to an acceptable value. This comes from the large resistive voltage drop in the thicker LiCl film on the anode of the stored cell. Thus, Li-sulfuroxychloride cells are characterized by a voltage delay which is defined as the time it takes for the cell potential to attain a value of 2 volts after it has been placed under load. The voltage delay time varies from seconds to hours, depending on the type of oxychloride cell, the storage period, storage temperature, and the load value. Under certain conditions, such as storage at 70.degree. C. for two weeks or more followed by discharge at high current densities.gtoreq.10 mA/cm.sup.2, the voltage of the cell may never recover to 2 volts. In general, the voltage delay problem is a serious deficiency of lithium-sulfur oxychloride cells.